Lemans 1000 points arcing

[lazlokovacs]

Hi,

I've had an intermittent RH cylinder for a while so I've been going through the ignition system...

I've fitted new points, new condensers and new coils and I'm still getting arcing at the points..

Any ideas?

the wires from the distributor to the coil (the red and green) are looking old and the copper inside looks dull and dark, could bad wires cause the arcing?

thanks

[guzzisteve]

Change the red & green wires if the copper has turned to a black color. You might try a Dyna 3 also.

[Triple Jim]

A points system works fine when it's in good condition.  Is the right points set arcing but the left not arcing?  There's always a little bit of arcing between the points if you look carefully in a dark room.  I doubt if old dark copper wires are your problem, but dark copper means moisture is getting past the insulation, and replacing that wire is cheap and not difficult.

Did you replace the spark plug wires and caps themselves?  They can get bad and intermittently arc to ground, causing an intermittent misfire.  Some plug caps have a built-in resistor that can fail and cause problems.

Have you replaced the spark plugs?

What coils did you buy?  What is their primary resistance?

[rodekyll]

Like Jim says, a spark at the points is normal.  It's what happens as you make/break connections.  The condenser's job is to minimize the spark, not eliminate it.  Arcing is different than sparking.  Jim's advice to compare the two sparks is solid.  Also, (sorry -forgot) evidence of arcing points are deeply pitted contacts and a deep blue/purple burned color (best compared to known good/used points because all points pit and discolor to a degree).

[Groover]

You could also have a faulty new condenser. Happened to me, and it caused me to change the coils thinking I had new everything else, when in the end, it just ended up being a bad condenser. If you still have the old ones, try temporally connecting that one to that side circuit and see how it goes.

[Greg Field]

Hi,

I've had an intermittent RH cylinder for a while so I've been going through the ignition system...

I've fitted new points, new condensers and new coils and I'm still getting arcing at the points..

Any ideas?

the wires from the distributor to the coil (the red and green) are looking old and the copper inside looks dull and dark, could bad wires cause the arcing?

thanks

Saw the exact same thing once on my personal LM1000. The problem was that the "neck" on the carb float was stretching out and would eventually starve the float bowl, and this was starving that side and causing the points to arc, somehow. Pull both of your needles and lay them side-by-side. If one is longer, you have found your problem.

[lazlokovacs]

Saw the exact same thing once on my personal LM1000. The problem was that the "neck" on the carb float was stretching out and would eventually starve the float bowl, and this was starving that side and causing the points to arc, somehow. Pull both of your needles and lay them side-by-side. If one is longer, you have found your problem.

interesting, though both needles were out today and are the same length...

 everything seems to be running ok, but still a healthy blue spark at the points while its running... I'll keep riding and see how the points hold up with some miles...

[mtiberio]

You can switch condensors, coils, plug wires and plugs side to side to see if the problem switches as well...

I built this so I could test ignition stuff in the garage. Had a pile of stuff and I didn't know if it was good or not. Yea, I know it is not perfect, but as a first order it works...

[rodekyll]

You are disturbed by the color of spark at the points, but the bike runs good.  Is there a problem with the ignition system?

This is where the old diagnostic scope is invaluable.  It gives a visual interpretation of everything that's happening in the ignition circuit.  Since you're unable to 'read' the points themselves (at least you're not reporting back on the visual cues we've listed), finding someone with a scope might be your best bet.  You could discover that the blue spark is 'normal' for your bike.

[Kiwi_Roy]

I'm still trying to figure out how he sees the spark with the distributor cap on,
Why are we talking coils (plural) with a distributor, one coil Shirley.
If the cap's off terminate the HT lead from the coil with a spark plug so it's normal.

Thinking out loud:
Is it possible that the distributor is out of line with the rotor when the points open i.e. a larger gap, I think a close examination of the inside of the cap would reveal that.
On that note is it possible the cap is out of line like the RH spark going out through the connection intended for the LH cylinder. Is the rotor cap symmetrical or is there an offset to account for the uneven firing order?

[rodekyll]

If this is a dual-point system with twin coils the cap can be off.  It's just a dust cover -- no HT or rotor.

[lazlokovacs]

If this is a dual-point system with twin coils the cap can be off.  It's just a dust cover -- no HT or rotor.

precisely

[Kiwi_Roy]

If this is a dual-point system with twin coils the cap can be off.  It's just a dust cover -- no HT or rotor.

Ok, I should have looked at the diagram before I put my keyboard in gear.
So it's just like a sterio then compare one side with the other.
It has a common feed so with the points open If I connect my ammeter to the load side of each coil to chassis the current draw should be equal producing a similar spark at the plug, that would test the coil & condenser. If different swap the condensers side to side and try again.
Measure the contact resistance from chassis, is it the same?
Is it possible you have different points like a Bosch in one side an Asian knock off in the other.
I still want to know the resistance from plug cap to chassis for each side.

[rodekyll]

I still don't have any confidence that the blue spark indicates anything more than a blue spark.  If the bike is running ok and nothing you do changes it, is it a problem?

The contact points are tungsten.  That's because spark is expected, and tungsten is very stable with sparks.  We've asked before if this is a spark or an arc.  An arc would be literally eroding one side of the points and depositing the eroded metal on the other, giving a pit-and-fang presentation.  The metal would be burned-looking with very 'bruised' looking discoloration.  Which side has the pits and which has the fangs tells you if the coil or the condenser side is the problem.  Also, comparing the two sets of points will show a monster difference if one side has a problem.  A normal deposit has minor pitting, little if any fang, and a grayish-to-bluish color. 

We've gotten no reports back from any of this.  I'll drop out of the discussion until there is some meaningful response.  To continue without some feedback is a waste of time.  Pics of the two points' contact surfaces would really help.

[lazlokovacs]

I still don't have any confidence that the blue spark indicates anything more than a blue spark.  If the bike is running ok and nothing you do changes it, is it a problem?

The contact points are tungsten.  That's because spark is expected, and tungsten is very stable with sparks.  We've asked before if this is a spark or an arc.  An arc would be literally eroding one side of the points and depositing the eroded metal on the other, giving a pit-and-fang presentation.  The metal would be burned-looking with very 'bruised' looking discoloration.  Which side has the pits and which has the fangs tells you if the coil or the condenser side is the problem.  Also, comparing the two sets of points will show a monster difference if one side has a problem.  A normal deposit has minor pitting, little if any fang, and a grayish-to-bluish color. 

We've gotten no reports back from any of this.  I'll drop out of the discussion until there is some meaningful response.  To continue without some feedback is a waste of time.  Pics of the two points' contact surfaces would really help.

points show no sign of unexpected pitting, I would take a picture but I'm not in the digital age camera-wise so and I don't have my own dark-room so it would take a while...

I just discovered that there is a big voltage drop going to my coils, as discussed in another thread, maybe this has something to do with it. I'm fitting new wires to everything ignition related, crimping and soldering and keeping the connections shiny...

As soon as the bike is running properly again, I'll put some miles on it and then report back on whether the sparks are pitting or fanging the points...

Thanks for everybody's input, it is much appreciated.


 

[Triple Jim]

I just discovered that there is a big voltage drop going to my coils, as discussed in another thread, maybe this has something to do with it.

What voltage are you reading at the coils?  Specifics are really helpful.  Some systems have a resistor in the supply to the coils, so a drop would be expected.  Can you trace the coil wire back toward the battery and determine if there's a resistor in there somewhere?

[pressureangle]

What voltage are you reading at the coils?  Specifics are really helpful.  Some systems have a resistor in the supply to the coils, so a drop would be expected.  Can you trace the coil wire back toward the battery and determine if there's a resistor in there somewhere?

I haven't seen a resistor on any bikes I've looked at (few) or wiring schematics (many)

[Triple Jim]

No, but they could have been added.  I just want to be sure that there aren't resistors in the circuit giving a false impression of low voltage.  I added resistors to my Mille when I had 3Ω coils installed.

[Kiwi_Roy]

Probably Ignition Switch Voltage drop, yawn!